Semiquinones are important intermediates postulated to be involved in the cytotoxic activities of quinone-containing drugs. The efficacy of these activities should depend on the thermodynamic stability of the semiquinones. This stability depends on the internal structure of the semiquinones and on the semiquinone-environment infractions. It is the purpose of this subproject to determine the thermodynamic parameters controlling the internal stability of semiquinones as well as semiquinone-environment interactions. Once these thermodynamic parameters are known, their effect on semiquinone redox reactions with oxygen, including lipid peroxidation, will be determined. Students will be trained in this subproject in all the aspects of the biomedical research process with the purpose of promoting them to biomedical research careers.